The Core Pharmacology Laboratory Unit of the University of California, San Francisco will be responsible for drug concentration measurements and pharmacokinetic analysis to support pharmacologic investigations of drugs used in the treatment of HIV infection and associated opportunistic infections. The laboratory will function as a central facility for ACTG trials for the routine analysis of drug and metabolite concentrations in biological fluids (e.g. zidovudine) and will be responsible for the development and implementation of chemical or biological assays for new therapeutic agents. In addition, laboratory personnel will provide consultation on study design and analysis including performance of pharmacokinetic and pharmacodynamic analysis. The Core Pharmacology Laboratory Unit has been a core laboratory facility for the ACTG for the last 5 years. Personnel of this laboratory are experienced in chemical and biological assay development and routine drug level measurement having developed or implemented assays for numerous agents, e.g. zidovudine (ZDV), GZDV, foscarnet, AzdU, GM-CSF, dapsone, trimethoprim, and sulfamethoxazole. Assay methodologies currently in use include HPLC, gas chromatography, ELISA, radioimmunoassay, and fluorescent polarization. All new drug assay development will be carried out by experienced research chemists and performed by staff research associates assay development for measurement of intracellular ZDV and its phosphorylated anabolites in monocyte/macrophage and lymphocyte fractions. Procedures utilized for pharmacokinetic analysis include compartmental and non-compartmental methods using microcomputer programs such as PC NONLINR and SIPHARR. For population based pharmacokinetic studies and pharmacodynamic studies, NONMEM and Emax modeling procedures will be used.